1. Field of the Invention
The invention relates to a polisher for chemical mechanical planarization, and more particularly, to a polishing pad structure and a polishing environment thereof.
2. Description of the Related Art
Recently chemical/mechanical polishing (CMP) has been developed for providing smooth topographies. Parameters which affect the polish removal rate are downward pressure on the wafer, rotational speeds of the polishing platen and wafer carrier, slurry particle density and size, composition and temperature of slurry and polishing pad. Adjustment of these parameters permits control of the polishing and planarization processes; however, the problem of non-uniform polish removal rate continues to plague conventional CMP processes because, in general, removal rate is lower at an initial stage of CMP process or during a wet idle period due to high modulus of the polishing pad, and then gradually tend to be higher since the effect of raised temperature on friction during the CMP process causes low modulus of the polishing pad, as shown in FIG. 1.
One improvement in CMP to control uniformity is the use of cooling water underneath the polishing pad to control temperature thereof. However, extra facility modification of the polisher is required.
In U.S. Pat. No. 6,818,301, Yaw S. Obeng et al disclose a polishing pad structure utilizing the incorporation of filler particles into the polishing body, thereby enhancing its polishing characteristics in certain applications. The filler particles may include an anion comprised of hydroxide capable of decomposing to oxide and water during chemical-mechanical polishing, thereby enhancing polishing planarization. Moreover, such decomposition may be endothermic, thus providing an additional means of thermal management. Decomposition means a compound breaks down into two or more substances. However, the endothermic heat produced by the decomposition reaction may be not enough to balance the effect of the increased temperature from friction.